The near universal adoption of Internet protocol (IP) as a standard for digital transmission is revolutionizing the traditional way of video delivery. Typical applications such as IPTV and live video streaming have become increasingly popular over the Internet. To efficiently utilize the bandwidth resources of the network in these applications, the video is usually compressed with suitable media coding schemes and then delivered only to subscribers who request it. For data delivery, multicast is considered the most efficient paradigm for such applications, but the scalability issue of traditional IP multicast hinders the deployment of a large-scale video delivery system with numerous channels.
The time it takes for a new program channel to start playing from the time a request to change to that channel is issued is a critical quality of experience (QoE) metric for multicast IPTV systems. Typical solutions to address channel changing in an IPTV environment involve unicasting a full-quality boost stream, or a portion thereof, replicated from a dedicated server provided for each service channel. However, such solutions can impose significant resource demands on the networks and associated streaming server infrastructure, thereby negatively impacting scalability. Other solutions focus on generating low-quality streams, composed of just I-frames or several low resolution channels, to accompany the regular channel stream. These mechanisms may engender noticeable picture inconsistency at each channel changing act, thereby degrading QoE to unacceptable levels.
Further, consumers are increasingly expecting flexible behavior from their video services, including live and/or on-demand offerings via IPTV platforms, to enhance available viewing options and features. However, traditional multicast environments supporting a single bitrate of content are largely unsuitable for providing a rich user experience.